Up to 1895, the Carolina deposits, which were worked chiefly by the Welsbach Light Company of New York, either directly or indirectly, supplied all the demand, but in that year the Brazilian sands were first worked, and a keen struggle commenced for the market. The American companies, after keeping up a considerable output for some years, were forced to suspend operations in May 1910. The Brazil deposits, worked by the German Thorium Syndicate and the Austrian Welsbach Company, which have an agreement, now meet practically the whole demand. The Brazilian sand occurs chiefly along the shores of the southern provinces, having been concentrated by the action of the tides from the products of erosion of the cliffs; it is very uniform and considerably richer than the Carolina sand, and owing to its occurrence on the sea-shore, the cost of transporting it is very low. It is exported chiefly to Germany, recently also to the United States, and to a small extent lately to England. The method of working it is similar to that employed in Carolina--namely, concentration by washing and magnetic separation. THE NORTH AMERICAN DEPOSITS[119] [119] See Nitze, _Bull._ No. 9, _N. Carolina Geol. Survey_, 1895; also Test, _Colorado School of Mines Bull._ Vol. IV. No. 2, p. 125, Jan. 1908. There are two important regions in North America within which monazite sands occur; one extends over the Carolinas, and the north-western part of Georgia, the other over the Idaho basin and neighbouring counties of the Pacific Slope. It will be best to treat these separately, as the deposits are somewhat different in character. (_a_) ~The Carolina Deposits~, including the unimportant Georgia deposits, which belong to the same field, occur over an area approaching 4000 square miles. The area is occupied chiefly by the Piedmont plateau, which is drained by a number of streams rising in the South Mountains, an eastern outlier of the Blue Ridge; it is in the basins and valleys of these streams, particularly at the head-waters, that the monazite is chiefly found. The geology of the district is very complicated,[120] the rocks being very highly altered granites. The chief bed is known as the Carolina gneiss, and includes several types of gneiss, usually very much weathered. The sands, which average about 1 per cent. of monazite, are worked in and near the stream beds; they occur in the beds, and in layers 1 to 2 feet in thickness a few feet below the surface of the surrounding soil. [120] See Sterret, _U.S. Geol. Survey_ (_Minerals_), 1906, p. 1195.